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            <div><h3 class="title">
                <a name="asio.reference.AsyncRandomAccessReadDevice"></a><a class="link"
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                                                                            title="Buffer-oriented asynchronous random-access read device requirements">Buffer-oriented
                asynchronous random-access read device requirements</a>
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    <p>
        In the table below, <code class="computeroutput"><span class="identifier">a</span></code> denotes
        an asynchronous random access read device object, <code class="computeroutput"><span class="identifier">o</span></code>
        denotes an offset of type <code class="computeroutput"><span class="identifier">boost</span><span
            class="special">::</span><span class="identifier">uint64_t</span></code>,
        <code class="computeroutput"><span class="identifier">mb</span></code> denotes an object satisfying
        <a class="link" href="MutableBufferSequence.html" title="Mutable buffer sequence requirements">mutable buffer
            sequence</a>
        requirements, and <code class="computeroutput"><span class="identifier">h</span></code> denotes
        an object satisfying <a class="link" href="ReadHandler.html" title="Read handler requirements">read handler</a>
        requirements.
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        <a name="asio.reference.AsyncRandomAccessReadDevice.t0"></a>
        <p class="title"><b>Table 4. Buffer-oriented asynchronous random-access read device requirements</b></p>
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            <table class="table" summary="Buffer-oriented asynchronous random-access read device requirements">
                <colgroup>
                    <col>
                    <col>
                    <col>
                </colgroup>
                <thead>
                <tr>
                    <th>
                        <p>
                            operation
                        </p>
                    </th>
                    <th>
                        <p>
                            type
                        </p>
                    </th>
                    <th>
                        <p>
                            semantics, pre/post-conditions
                        </p>
                    </th>
                </tr>
                </thead>
                <tbody>
                <tr>
                    <td>
                        <p>
                            <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span
                                    class="identifier">get_executor</span><span class="special">()</span></code>
                        </p>
                    </td>
                    <td>
                        <p>
                            A type satisfying the <a class="link" href="Executor1.html" title="Executor requirements">Executor
                            requirements</a>.
                        </p>
                    </td>
                    <td>
                        <p>
                            Returns the associated I/O executor.
                        </p>
                    </td>
                </tr>
                <tr>
                    <td>
                        <p>
                            <code class="computeroutput"><span class="identifier">a</span><span class="special">.</span><span
                                    class="identifier">async_read_some_at</span><span class="special">(</span><span
                                    class="identifier">o</span><span class="special">,</span>
                                <span class="identifier">mb</span><span class="special">,</span>
                                <span class="identifier">h</span><span class="special">);</span></code>
                        </p>
                    </td>
                    <td>
                        <p>
                            <code class="computeroutput"><span class="keyword">void</span></code>
                        </p>
                    </td>
                    <td>
                        <p>
                            Initiates an asynchronous operation to read one or more bytes of
                            data from the device <code class="computeroutput"><span class="identifier">a</span></code>
                            at the offset <code class="computeroutput"><span class="identifier">o</span></code>.
                            The operation is performed via the <code class="computeroutput"><span class="identifier">io_service</span></code>
                            object <code class="computeroutput"><span class="identifier">a</span><span
                                class="special">.</span><span class="identifier">get_io_service</span><span
                                class="special">()</span></code>
                            and behaves according to <a class="link" href="asynchronous_operations.html"
                                                        title="Requirements on asynchronous operations">asynchronous
                            operation</a> requirements.<br> <br> The mutable buffer
                            sequence <code class="computeroutput"><span class="identifier">mb</span></code> specifies
                            memory where the data should be placed. The <code class="computeroutput"><span
                                class="identifier">async_read_some_at</span></code>
                            operation shall always fill a buffer in the sequence completely
                            before proceeding to the next.<br> <br> The implementation
                            shall maintain one or more copies of <code class="computeroutput"><span class="identifier">mb</span></code>
                            until such time as the read operation no longer requires access
                            to the memory specified by the buffers in the sequence. The program
                            must ensure the memory is valid until:<br> <br> — the last copy
                            of <code class="computeroutput"><span class="identifier">mb</span></code> is destroyed,
                            or<br> <br> — the handler for the asynchronous read operation
                            is invoked,<br> <br> whichever comes first.<br> <br> If
                            the total size of all buffers in the sequence <code class="computeroutput"><span
                                class="identifier">mb</span></code>
                            is <code class="computeroutput"><span class="number">0</span></code>, the asynchronous
                            read operation shall complete immediately and pass <code class="computeroutput"><span
                                class="number">0</span></code> as the argument to the handler
                            that specifies the number of bytes read.
                        </p>
                    </td>
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            <div class="copyright-footer">Copyright © 2003-2022 Christopher M. Kohlhoff<p>
                Distributed under the Boost Software License, Version 1.0. (See accompanying
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